The officials, who spoke on the condition of anonymity because they were not authorized to speak publicly, said the process could take months as it goes through the judicial system. On Saturday, the attorney general of Mexico, Arely Gómez González, said for the first time that the government took preliminary steps to proceed with Mr. Guzmán’s extradition as far back as July, shortly after his escape from prison.

Guzmán can challenge the Mexican government's move and is expected to do so. He has been indicted at least seven times in U.S. federal courts on drug and murder charges.